1. Field of the Invention
The present invention relates to a defect management method for a recording medium, and more particularly to a structure of a writable optical disc and a method and apparatus for managing defective areas of the writable optical disc.
2. Description of the Related Art
Recently, new high-density optical discs, which can store a large quantity of high-quality video and audio data, have been developed. In accordance with such development, blu-ray disc rewritable (BD-RE) and blu-ray disc write-once (BD-WO) are expected to be commercially available in the near future.
Referring to FIG. 1, the structure of a BD-RE is illustrated. As shown in FIG. 1, the BD-RE has a lead-in area (LIA), an information area, and a lead-out area (LOA). Also, an inner spare area (ISA) and an outer spare area (OSA) are assigned at the leading and trailing ends of the information area. The LIA includes a defect management area (DMA). The DMA stores disc definition structure (DDS) information and defect list (DFL) information required for management of defective areas.
An optical disc apparatus records and reproduces data to and from the BD-RE of FIG. 1. Particularly, the optical disc apparatus encodes and modulates data, externally inputted thereto, into a signal suitable to be recorded, and records the modulated signal on the BD-RE in the unit of clusters each corresponding to an error correction code (ECC) block. When the optical disc apparatus detects a defective area in the information area of the BD-RE during the recording operation, as shown in FIG. 1, it performs, in a spare area of the BD-RE, replacement recording of the cluster-based data to be recorded in the detected defective area.
The optical disc apparatus also manages the DFL information used to access data recorded in the spare area of the BD-RE as replacement data. The DFL information includes a plurality of defect entries Defect_Entry #1, #2, #3, . . . each having a fixed size of, for example, 4 clusters. Positional information about a defective area (“Physical Sector Number (PSN) of Defective”), and positional information about a spare area in which replacement data corresponding to data to be recorded in the defective area has been recorded (“PSN of Replacement”), are recorded and associated with each other, in each defect entry.
When the optical disc apparatus detects a defective area during an operation of recording data in the information area of the BD-RE, it performs, in a spare area of the BD-RE, replacement recording of cluster-based data to be recorded in the detected defective area, generates associated DFL information, and records the generated DFL information. Upon subsequently performing a reproduction operation, the optical disc apparatus reads and reproduces the replacement data recorded in the spare area while referring to the recorded DFL information. Thus, it is possible to prevent erroneous recording of data.
When a defective area on the BD-RE is detected during an operation of recording data in the information area of the BD-RE, it is necessary to jump an optical pickup of the optical disc apparatus to a spare area of the BD-RE so as to record cluster-based data, to be recorded in the detected defective area, in the spare area as replacement data. After completion of the replacement data recording operation, it is also necessary to again jump the optical pickup to a position, which follows the position of the detected defective area, to continue with the recording operation. For this reason, the structure and use of the BD-RE of FIG. 2 have a problem of requiring a longer recording operation time. Furthermore, the jumping operations may generate errors since they require optical elements of the optical disc apparatus to be moved quickly and precisely.
Moreover, where such a large inner spare area or outer spare area is assigned to completely record replacement data corresponding to data of all defective areas, the data recording capacity of the optical disc is excessively reduced. On the other hand, where a small inner spare area or outer spare area is assigned, the possibility of generation of errors during the replacement data recording operation may increase.